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Questions tagged [physical-chemistry]

The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.

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3answers
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Choice of doping elements in semiconductors

In a typical semiconducting material, we start with silicon (group IV) and introduce atoms of group V or group III depending on whether we are constructing an n- or p-type semiconductor respectively. ...
9
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1answer
14k views

How does dimethylsulfoxide serve as a cryoprotectant?

In cell culture, dimethylsulfoxide (DMSO) is added to prevent the formation of ice crystals which may lyse the cells. Exactly how does dimethylsulfoxide act as a cryoprotectant?
161
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8answers
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Can an atom have more than 8 valence electrons? If not, why is 8 the limit?

According to some chemistry textbooks, the maximum number of valence electrons for an atom is 8, but the reason for this is not explained. So, can an atom have more than 8 valence electrons? If ...
14
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1answer
617 views

Are there any examples of nuclear spin isomers having consequences for chemical reactivity?

Ortho- and parahydrogen are two forms of the $\ce{H2}$ molecule that are distinguished by their pairing or antipairing of nuclear spins, giving rise to metastable singlet (ortho-) and triplet (para-) ...
21
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4answers
38k views

what kind of suspension liquid should be used with ferrofluid (so it does not stain the glass)

Please take a look at the following video: I am working on a new project, and I need to find whats the best liquid to hold ferrofluid inside the glass (or maybe even plastic) container, so that ...
10
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1answer
3k views

What's the difference between precipitate and turbidity?

In many tests for various radicals, a "<color> precipitate" or "<color> turbidity" is mentioned. For example, lead ...
23
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5answers
895 views

Why are equations of state for a non-ideal gas so elusive?

The ideal gas equation (daresay "law") is a fascinating combination of the work of dozens of scientists over a long period of time. I encountered Van der Waals interpretation for non-ideal gases ...
26
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3answers
19k views

Why does ice cream make soda fizz?

I've noticed that adding a chunk of ice cream to soda makes the soda fizz slightly near the soda-ice cream interface. I thought it was a physical effect due to the temperature, but adding ice has no ...
18
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1answer
635 views

When simulating spectral line broadening, which convolution is preferred?

Many computational chemistry packages permit the calculation of vibrational and electronic spectra. These spectra are obtained as a set of discrete eigenvalues however they are often convolved with ...
0
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1answer
4k views

Are there endothermic dissolution reactions? [closed]

Are there reactions like $X(s) + n Y(l) \to X \centerdot Y_n(l)$ that are endothermic? What are X and Y then? The material X should also be soluble to material Y.
10
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2answers
7k views

Gas chromatography/mass spectrometry: Can I use peak ratios and molecular mass to derive quantity?

Can derive the quantity of a substance from a GC/MS report if I know: the ratio to another substance in the data, the quantity of that second substance, and the molecular mass of both substances. ...
15
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1answer
384 views

How does conductivity work for non-redoxed ions?

Related (very similar, but here I want a mechanism) https://physics.stackexchange.com/q/21827/7433 By the Kohlrausch law, all ions contribute to the conductivity of an electrolyte. Now, as I ...
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2answers
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What are the major factors that influence LogP

The partition coefficient is a very useful metric in characterizing compounds particularly drugs. What chemical properties influence that partitioning? Are chemical moieties additive in their LogP? ...
9
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6answers
3k views

A quick method for separating liquids?

I'm looking for a way to take 3 separate liquids (liquids which function as paint -- they will all be different colors), put them together into a container, and then rapidly separate them back to ...
12
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4answers
54k views

General rules for deciding volatility

Given an organic compound, is there any way to decide if it is volatile (or compare volatility--everything is volatile in the end)? Volatility is due to the tendency to evaporate. The conclusion I ...
20
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2answers
11k views

Why is distillation not a viable way to seperate ammonia from water?

Since the steam pressure of ammonia is higher than that of water, I would expect distillation to be a reasonable way of seperating a mixture of both. However, in industrial applications known to me ...